Charge injection and transport in electrochemical films of poly(3-hexylthiophene)

We have produced and characterized poly(3-hexylthiophene) (PHT) thin films by electrochemical deposition onto tin–oxide (TO) or gold covered glass substrates. PHT film thickness and roughness depend on deposition charge density and are also dependent on substrate material. From electrical measurements we determine an electrical conductivity of 9×10−5 S cm−1 when Ni and Au electrodes are used. An energy barrier of 0.8 eV for positive charge carrier injection into PHT at Al/PHT and TO/PHT interfaces was determined. We estimate the mobility of positive charge carriers in electrochemically deposited PHT as being 1×10−4 cm2 V−1 s−1. An energy diagram of PHT is proposed.